IUPAC naming: parent chains, branches and location numbers
≈ 50 minIUPAC naming: parent chains, branches and location numbers
A systematic organic name is a compact structural map. Identify the highest-priority functional group in the question, choose the longest parent chain containing it, number to give that group then substituents the lowest possible positions, name branches with prefixes such as methyl or bromo, and attach the correct suffix. Use commas between numbers and hyphens between numbers and words. Structural isomers may share a molecular formula but need different names because their atoms are connected differently. Check that the number of carbons in the name matches the structure before finalising.
Work it through
For CH₃CH(CH₃)CH₂CH₃, the longest chain has four carbons, so the parent is butane. The methyl branch is on carbon 2 when numbered from the nearer end: 2-methylbutane. Calling it 3-methylbutane uses a valid-looking but non-lowest position number and is not the preferred name.
Mastery target
Name branched organic molecules using a defensible parent-chain choice, lowest-location numbering and correctly ordered prefixes and suffixes.
What is the preferred name for CH₃CH(CH₃)CH₂CH₃?
Name the key chemistry term from IUPAC naming: parent chains, branches and location numbers that best fits the explanation and visual model.
What does a prefix such as methyl describe in an organic name?
Which statement corrects a common misunderstanding in IUPAC naming: parent chains, branches and location numbers?